Linear polyacrylamide is an efficient carrier for precipitation of picogram
amounts of nucleic acids with ethanol. It is cheap,easy to make and can
be stored in refrigerator for several years. For complete reference of the
method see: Ethanol precipitation of DNA with linear polyacrylamide as carrier.
Gillard, C and Strauss F. Nucleic Acid Research, Vol. 18. No. 2. page 378.
1990.

Add 1/100 volume of a 10% solution of ammonium persulfate and 1/1,000 volume
of TEMED. Mix it gently and let polymerize for 30-60 minutes.

When the solution has become viscous, add 2.5 volumes of ethanol to precipitate
the polyacrylamide. Mix it and let stand it for 10-15 minutes.

Centrifuge the precipitated polyacrylamide at 10,000 rpm for 10 minutes.

Remove the supernatant and dissolve the pellet in 20 volumes of water by
shaking overnight.

The polyacrylamide solution (0.25% final concentration) can be stored in
refrigerator for several years. Aliquot part of the sample in eppendorf
tubes (100 ml per tube) so you may not contaminate
the stock by continuously mowing it in and out from the refrigerator.

For DNA precipitation add 10-15 ml of the linear
polyacrylamide to the DNA solution to be precipitated. Proceed with the
standard precipitation procedure